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April 21, 2009 -- Ovary removal during a hysterectomy is often done to reduce the risk of ovarian cancer. But doing so also boosts the risk of heart disease and death long-term, according to a new study.

For women without a strong family history of ovarian cancer or genetic predisposition to it, these heart disease and death risks appear to outweigh the benefit of the decreased cancer risk, says William H. Parker, MD, the study's lead author and a gynecologic surgeon and researcher at the John Wayne Cancer Institute at St. John's Health Center, Santa Monica, Calif. The study is published in the May issue of Obstetrics & Gynecology.

It's time to rethink the routine removal of ovaries, Parker says. "For the past 35 years, any woman over 40 or 45, when they needed a hysterectomy, would be told by the doctor, 'We should take out the ovaries to prevent ovarian cancer,'" Parker tells WebMD.

Ovary Removal or Not? Study Details

Although the advice to remove the ovaries is undoubtedly good for women at high risk for ovarian cancer, Parker began to wonder years ago if the advice was sound for the general population, whose overall risk of ovarian cancer is typically low, especially in comparison to other health risks as they age, such as heart disease.

To find out, Parker and his colleagues from Harvard Medical School and numerous other institutions tracked the health outcomes of 29,380 women participants in the long-running Nurses' Health Study. All had a hysterectomy for reasons other than cancer. More than half, or 16,345, had both ovaries removed; the other 13,035 women kept their ovaries.

Ovary Removal or Not? Study Results

After 24 years of follow up, the researchers found some health risks increased among those who had their ovaries removed compared to those who did not. Among them:

The risk of death from any cause increased 12%.

The risk of heart disease -- sometimes fatal -- increased by 17%. Put another way, for every 130 women who have both ovaries removed during hysterectomy, one extra death from heart disease will occur that is directly attributed to the ovary removal.

As expected, the risks of ovarian and breast cancer declined in those who had ovary removal. Breast cancer risk declined by 25%, ovarian cancer totally, Parker says.

Among the more than 13,000 women who kept their ovaries, 99 got ovarian cancer and 34 died.

Ovary Removal or Not? Perspective

"Ovarian cancer is a terrible disease and we still don't know how to find it early, cure it," Parker says. "But compared to heart disease, it is a rare cause of death."

For years, he says, doctors have talked about the value of routine ovary removal during a hysterectomy to reduce ovarian cancer risk. "Now that is overshadowed by all these other risks that are much more common and much more likely to kill you."

"What our study shows is taking out a woman's ovaries during hysterectomy isn't always the best option and that women need to be sure they discuss the risks and benefits about leaving their ovaries or taking out their ovaries with the doctor," Parker says.

His latest study confirms the findings of his study published in 2005, in which he and colleagues did a computer model type of study, feeding the results of several different studies into the computer and finding survival benefits with keeping the ovaries for women younger than age 65 at the time of surgery.

Other research has also found that routine removal of the ovaries increases the risk for heart disease, stroke, osteoporosis, and dementia.

It's presumed that the protective effect of keeping the ovaries is because of estrogen, Parker says. After menopause, the ovaries continue to make testosterone (which is converted into estrogen by fat cells) and small amounts of estrogen.

The study was funded by a research arm of Ethicon Women's Health, a company that makes treatments for women's health problems. Parker has served as a consultant for the company.

Ovary Removal or Not? Second Opinions

The study conclusion -- that preventive removal of the ovaries should not be automatic -- makes sense, says Alan DeCherney, MD, the editor-in-chief of Fertility and Sterility and director of the program in reproductive and adult endocrinology at the National Institutes of Health's National Institute of Child Health and Human Development in Bethesda, Md.

"I agree with the conclusion," he tells WebMD. "It's an important health lesson. Every patient is an individual."

For women, the message from this study, he says, is this: "If you don't have a reason to have your ovaries removed, they should be left in."

In 2008, the American College of Obstetricians and Gynecologists issued a practice bulletin for its members on ovary removal. In it, it suggests "strong consideration" be given to retain normal ovaries in premenopausal women who are not at increased genetic risk of ovarian cancer, but that ovarian removal at the time of hysterectomy be considered for postmenopausal women.

DeCherney suspects the guidelines will be revisited in the wake of the current study.

Another fertility specialist, Richard Paulson, MD, chief of reproductive endocrinology and infertility at the University of Southern California's Keck School of Medicine, says the study strongly suggests that "for women at low risk of ovarian and breast cancer, there is no reason for taking the ovaries out."